For my next recipe I would like to have a thin mash, say 3 gallon and sparge with about 6 gallons. The total boil would then be 9 gallon. Unfortunatly my boiler is only 5 gal.

I was thinking of extracting 3 gallons of first runnings, sparge with 3 gallons, resparge with the second runnings. Is there a problem with this method? Will this extract not enough sugar, more tannins or any other problems?

Without thinking about it too much, or doing any calculations, I'm thinking you'll end up with a very low grav beer. In a 5 gallon boiler, the most grain you'll really be able to mash is roughly 10-11 pounds, give or take. I'm thinking of doing the same thing this week with my 5 gallon kettle, but I'm making a 5 gallon batch of 1.048 beer. I think with 9 gallons, and no more than 11 pounds of grain, your gravity will be very low.

This is coming from someone who has never done AG before, so please correct me if my assumptions are incorrect.

I mostly brew OG 1.080 beers. Will i be able to sparge with the wort several times to extract enough sugars?

Marius

I wouldn't do this. Figure out a way to use fresh water and do a longer boil. You are rinsing the grains to extract sugar. Your proposed method would be like washing your clothes twice, the second time with dirty water and expecting them to be cleaner

I wouldn't do this. Figure out a way to use fresh water and do a longer boil. You are rinsing the grains to extract sugar. Your proposed method would be like washing your clothes twice, the second time with dirty water and expecting them to be cleaner

Several confusing points. You say "thin mash" but a 3 gallon mash for a 1.080 beer would be what I'd call a "thick mash". However, it sounds like you might be trying to do a partial mash and make up some gravity with extract.

You can't sparge with wort. The new wort that drains out will be the exact same gravity that it went in at because the wort that's stuck in the grain is the same gravity.

A partial mash with about 8 pounds of grain, 4 gallons "no sparge" would work in that 5g kettle. Make up the remaining gravity with extract.